1988 - Transformers: Super God Masterforce

Transformers: Super God Masterforce ("Choujin Masterforce") aired on Japanese television from 1988 to 1989. Though the Destrons have been driven away from Earth following the events of Transformers: Headmasters, a small team of Cybertrons led by Metalhawk, have remained behind, using Pretender shells to disguise themselves as humans. Their caution is rewarded when when the planet is attacked by Destrons led by the mysterious Devil Z, who's searching for Transtectors, robot bodies hidden on Earth eons ago.

As the battles continue and Transtectors are uncovered, both sides recruit humans to control them with transforming armored suits. The Cybertrons' friends include the teenaged Junior Headmasters Shuta, Cab, and Minerva (Siren, Hosehead, and Nightbeat), as well as the brash trucker Ginrai (Powermaster Optimus Prime). Ginrai eventually leads the Cybertron Godmasters, and acquires Godbomber, a support trailer/robot drone that combines with God Ginrai to form Super God Ginrai.

Minerva is one of the most popular Masterforce characters among fans. I wonder why...

Humans allied with the Destrons include the thugs Wilder, Cancer, and Bullhorn (Fangry, Squeezeplay, and Horri-bull), the brothers Buster and Hydra (Dreadwing and Darkwind), and the spy Doubleclouder (Doubledealer). They are directed by Devil Z's lieutenants, Giga and Mega, who eventually get transtectors of their own -- an SR-71 Blackbird and a tank, which combine to form the fearsome Overlord.

The name Masterforce comes from the series' focus on the human Headmasters and Godmasters (Powermasters); when battle calls, they transform into a robot head or an engine, then combine with his or her transtector to become a robot. While most of the toys were released worldwide, Metalhawk was an exclusive for the Japanese market, so named because the robot inside his Pretender shell was made of metal.

Finally, according to the Masterforce backstory, the reason why God Ginrai looks like the Cybertron commander Convoy (Optimus Prime) is because Ginrai's transtector was originally intended to be a replacement body for the famous leader.